by Stuart Rosenblum, MD, PhD; Robert Fisher, MD; David Caraway, MD, PhD; and Michael Saulino, MD
Some patients find IT opioid therapy not effective despite a successful trial. I wrote a column on the failure of IT trials to predict success in the March 2007 issue of this journal (Vol 7: Issue 2). Fortunately, physicians have options to opioid IT therapy but need to know how to rotate from opioid IT therapy to an alternative IT therapy without causing the patient discomfort or side effects. This article by Rosenblum et al provides the readers an example of how this rotation can occur with minimal side effects and adequate analgesia throughout the rotation. Other physicians may have an equally effective method, but for these authors, the process described in this article seems to be safe and effective for them. It may provide the reader an option as well.
— Lynn Webster, MD, FACPM, FASAM
Department Head
Weaning a patient with chronic pain from intrathecal opioids may be considered in a number of circumstances. During the course of intrathecal opioid therapy, patients sometimes experience intolerable adverse events or develop tolerance to the opioid.1 Some patients may have an inadequate response (i.e., <25 percent reduction in pain and/or little to no functional improvement) to opioid therapy, opioid rotation, or combination therapy. In such cases, proper pump function and catheter placement and integrity should be confirmed before making the decision to wean the patient from intrathecal opioids. If no issues with the pump or catheter are found and the patient is unresponsive to intrathecal opioid treatment or experiences intolerable adverse events, weaning off intrathecal opioids and conversion to intrathecal therapy with nonopioid drugs—such as ziconotide or clonidine—may be considered. Lastly, weaning from intrathecal opioids may be necessary if pump explantation is either desired, as in the case of ineffectiveness, or required, as in the case of pump-related infection.
Weaning of patients with chronic pain from intrathecal opioid therapy can seem a challenging prospect. Many clinicians mistakenly adhere strictly to the belief that any decreases in intrathecal opioid doses should be replaced with equianalgesic doses of systemic opioids. Various equianalgesic oral to intrathecal dosing ratios have been suggested, ranging from 12-to-1 to 300-to-1.2,3 Such ratios are used for conversion from systemic dosing to intrathecal dosing, and one cannot assume that the ratios would be equivalent for conversion from intrathecal to systemic opioid dosing.3 Additionally, the ratios may be more suitably applied to acute pain patients. These equianalgesic doses are typically inappropriate for weaning from chronic intrathecal opioid therapy. Such patients can be weaned without strict adherence to equianalgesic conversion ratios.
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